1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Simple pointer stack 4 * 5 * (c) 2010 Arnaldo Carvalho de Melo <acme@redhat.com> 6 */ 7 8 #include "pstack.h" 9 #include "debug.h" 10 #include <linux/kernel.h> 11 #include <linux/zalloc.h> 12 #include <stdlib.h> 13 #include <string.h> 14 15 struct pstack { 16 unsigned short top; 17 unsigned short max_nr_entries; 18 void *entries[0]; 19 }; 20 21 struct pstack *pstack__new(unsigned short max_nr_entries) 22 { 23 struct pstack *pstack = zalloc((sizeof(*pstack) + 24 max_nr_entries * sizeof(void *))); 25 if (pstack != NULL) 26 pstack->max_nr_entries = max_nr_entries; 27 return pstack; 28 } 29 30 void pstack__delete(struct pstack *pstack) 31 { 32 free(pstack); 33 } 34 35 bool pstack__empty(const struct pstack *pstack) 36 { 37 return pstack->top == 0; 38 } 39 40 void pstack__remove(struct pstack *pstack, void *key) 41 { 42 unsigned short i = pstack->top, last_index = pstack->top - 1; 43 44 while (i-- != 0) { 45 if (pstack->entries[i] == key) { 46 if (i < last_index) 47 memmove(pstack->entries + i, 48 pstack->entries + i + 1, 49 (last_index - i) * sizeof(void *)); 50 --pstack->top; 51 return; 52 } 53 } 54 pr_err("%s: %p not on the pstack!\n", __func__, key); 55 } 56 57 void pstack__push(struct pstack *pstack, void *key) 58 { 59 if (pstack->top == pstack->max_nr_entries) { 60 pr_err("%s: top=%d, overflow!\n", __func__, pstack->top); 61 return; 62 } 63 pstack->entries[pstack->top++] = key; 64 } 65 66 void *pstack__pop(struct pstack *pstack) 67 { 68 void *ret; 69 70 if (pstack->top == 0) { 71 pr_err("%s: underflow!\n", __func__); 72 return NULL; 73 } 74 75 ret = pstack->entries[--pstack->top]; 76 pstack->entries[pstack->top] = NULL; 77 return ret; 78 } 79 80 void *pstack__peek(struct pstack *pstack) 81 { 82 if (pstack->top == 0) 83 return NULL; 84 return pstack->entries[pstack->top - 1]; 85 } 86